Until now, Android apps have been available only for free. The shift will make the platform a lot more attractive to professional developers, and will position the Android phone platform as a more serious competitor to the iPhone and other smartphones.

Free is great when you can get it, and the free software folks definitely have their place. But it's just not going to cut it in the consumer world. The profit motive still drives the bulk of development, and several of the major developers have been hesitant to develop for the Android platform for this very reason. With the shift to a for-profit Android applications marketplace, Google's going to take a big piece of the market as more developers see this as a brand new opportunity and start building serious consumer and business applications for the platform. Developers will keep 70 percent of the revenue from app sales.